The present invention relates to networked computer systems. In particular, the present invention relates to computing environments that are populated with networked workstations sharing network file systems. One known system for sharing idle resources on networked computer systems is the Condor system that was developed at the University of Wisconsin (idle resources refer, generally, to a networked workstation having no user input commands for at least a certain period of time). The Condor system is more fully described in M. Litzkow et al., "Condor--a hunter of idle workstations," Proc. ICDCS, pp. 104-111, 1988.
Some of the main disadvantages of the Condor system are as follows. Condor uses a centralized scheduler (on a centralized server) to allocate network resources, which is a potential security risk. For example, having a centralized server requires that the server have root privileges in order for it to create processes that impersonate the individual users who submit jobs to it for remote execution. Any lack of correctness in the coding of the centralized server (e.g., any "bugs") may allow someone other than the authorized user to gain access to other user's privileges. Secondly, the Condor system migrates the execution of a job on a remote host as soon as it detects any mouse or keyboard activity (i.e., user inputs) on the remote host. Therefore, if any user, including users other than the primary user, begins using the remote host, shared execution is terminated and the task is migrated. This causes needless migration and its concomitant work lossage. Thirdly, due to the nature of a centralized server, starting the server can only be accomplished by someone with root privileges.
Another known system for accomplishing resource sharing is the Coshell system (which is described more fully in the G. S. Fowler article "The shell as a service," incorporated by reference above). Coshell, unfortunately also has disadvantages, such as the fact that Coshell also suspends a job on the remote host whenever the remote host has any mouse or keyboard activity. Additionally, Coshell cannot migrate a suspended job (a job that was executing remotely on a workstation and was suspended upon a user input at the remote workstation) to another machine, but has to wait until the mouse or keyboard activity ends on the remote host before resuming execution of the job. The fact that Coshell suspends the job's execution in response to any mouse or keyboard activity creates needless suspensions of the job when any mouse or keyboard activity is sensed at the remote host.
It would therefore be desirable to provide systems and methods of more efficiently sharing computational resources between networked workstations.
It would also be desirable to provide program execution on idle, remote workstations in which suspension of the program execution is reduced to further increase processing efficiency.
It would be still further desirable to provide a network resource sharing architecture in which suspended jobs may be efficiently migrated to alternate idle workstations when the initial idle, remote workstation is once again in use by the primary user.